Flexible Sheets of Light

SAN FRANCISCO--Let there be light on the side of municipal buses.

That's the motto of CeeLite, a Blue Bell, Pa.-based start-up that has devised a thin, bendable light source that can be integrated into walls or wrapped around poles. The company is in the midst of trials with 32 cities, which are putting signs equipped with CeeLite's light on the sides of its buses.

The signs, which require only about 4 watts of power per square foot, can measure up to 12 feet long and 30 inches high, but they are less than an inch thick. The actual light source inside the signs is only about an eighth of an inch thick, but it can reach 6 feet long. (The 12-foot sign contains two light sources.)

The bus lights, of course, don't just blare white light at drivers and pedestrians. Transparencies emblazoned with advertisements are placed on top of the sheets, thereby making the ordinary bus advertisement pop.

"I want to light surfaces that aren't lit today. I want to light floors. I want to light floorboards,"

Mike Binder, senior vice president of business development, said during a presentation at the ThinkGreen conference here this week.

"I have the ability to light objects with the objects themselves."

And there are a lot of surfaces that can be exploited, he asserted. Recently, Binder spent a weekend in Las Vegas, where he visited 120 restaurants by himself to check out the market potential. There's a lot of unadorned real space, he said.

"Self-illumination is a massive untapped market."

CeeLite's signs are powered by a light-emitting capacitor, or LEC. LECs effectively store energy like standard capacitors, then release it into a substrate sprinkled with phosphors, which emit light when a current is applied. Different researchers and companies have worked on LECs and similar electroluminescent products for years, but the results weren't great. The products wore out over time or were relatively small.

"We figured out what makes EL (electroluminescence) fail,"

Binder said.

CeeLite's LEC, embedded between two polymer layers, is plugged into a power source. The company currently uses fresh plastic but is working on a way to use recycled plastic. Ideally, companies like Coca-Cola could make signs out of their old bottles.

From a functional standpoint, LECs are similar to organic light-emitting diodes. OLEDs, though, tend to be relatively small. Sony has released an 11-inch TV with an OLED screen, but the biggest customers for OLEDs right now are cell phone makers.

OLED makers like Universal Display, however, are also trying to get into the lighting market, where they say they'll be in a few years. They have also worked on the durability of their products, which they claim can last 20,000 hours.

One of the more novel OLEDs, from Universal Display, is a transparent piece of plastic that can serve as a window. Humans can see through it, but when a current is applied, it emits light.

Binder further added that CeeLite's signs are fairly durable. The signs can endure the pressure of power washers, which can spray water at several hundred pounds per square inch. To demonstrate, he also grabbed one of the company's lights, bent it several times and then jumped on it. It stayed lit.

Executives from hedge funds and private-equity firms gathered around to give him their cards.